One Step
Pregnancy Test Strip For Urine
(Revised Mar 30th, 2001)
1. 10-30 mIU/ml
2. 37,000-50,000 mIU/ml
3.
<5 mIU/ml
7-10 days post conception.
8-11 weeks after last menstrual period.
Healthy men or non-pregnant women.
Intended Use
The One Step hCG Urine Test is an immunoassay designed for the qualitative
determination of the human chorionic gonadotropin (hCG) in urine for the early
detection of pregnancy. It is intended for professional or laboratory use.
Standardization
The Pregnancy Urine Test will detect hCG concentrations of 20 mIU/ml or
greater (referenced to the World Health Organization First International
Standard).
Summary and Explanation of the Test
Human chorionic gonadotropin (hCG) is a glycopeptide hormone produced by the
placenta during pregnancy. The appearance and rapid increase in the
concentration of hCG in the mother’s urine makes it a good marker for
confirming pregnancy. The concentration of hCG in urine increases steadily to a
circulation peak of as much as 50,000 mIU/ml between the eighth and eleventh
weeks (1,2,3).
Performance Characteristics
Sensitivity
The Pregnancy Urine Test will detect hCG in urine at concentrations of 20
mlU/ml or greater. This sensitivity level has been confirmed with internal hCG
standards in urine, calibrated against the World Health Organization First
International Standard.
Specificity
The ability of the Urine hCG Pregnancy Test to specifically detect hCG was
challenged through cross-reaction studies on urine samples containing known
quantities of structurally and physiologically related hormones. Urine samples
spiked with 500mIU/ml LH (human Luteinizing Hormone), 1000 mIU/ml FSH
(Follicle Stimulating Hormone) and 1000 IU/ml TSH (Thyroid Stimulating
Hormone) show negative results only.
The One Step hCG Urine Test is a chromatographic immunoassay which uses
specific antibodies to selectively identify hCG in urine with a high degree of
sensitivity. Elevated levels of hCG as low as 20 mIU/ml can be detected within 3
minutes.
Principles of the Test
Urine is added to the test kit and allowed to migrate through the absorbent device.
The labeled antibody-dye conjugate binds to the hCG in the specimen forming an
antibody-antigen complex. This complex binds to the anti-hCG antibody in the
test zone and produces a purple color band when the hCG concentration is equal
to or greater than 20 mIU/ml. In the absence of hCG, no band is formed in the
test zone. The reaction mixture continues flowing through the absorbent device
past the test and control zones. Unbound conjugate binds to the reagents in the
control zone, producing a purple color band, demonstrating that the reagents and
the test kit are functioning correctly.
Reagents Used
The test kit contains combination of goat/rabbit polyclonal antibodies and mouse
monoclonal antibodies in a protein buffer containing sodium azide.
Precautions
(1) For in vitro diagnostic use only.
(2) Do not use after the expiration date imprinted on the test kit package.
(3) Dispose of all reaction devices in a proper biohazard container.
(4) Patient specimens may contain infectious agents and should be handled as
potential pathogens.
Test Kit Storage
The test kit may be stored at room temperature 4-30oC (40-86oF) for up to 18
months or until the expiration date. Optional Liquid control reagents may have
different storage requirements. Refer to individual components for their specific
requirements.
Urine Collection and Storage
(1) First morning urine typically contains the highest concentration of hCG and is
therefore the best sample for performing the urine test. However, any urine
specimen may be used.
(2) Collect the urine specimen in a clean glass or plastic container. Do not use
preservatives.
(3) If the specimen is not used immediately following collection, but is to be used
within 48 hours it should be refrigerated (2 to 8 oC), and brought back to room
temperature (4 to 30 oC) before testing. If the specimen is not going to be used for
more than 48 hours, it should be frozen at -20 degrees C. A frozen specimen
should not be used if stored longer than 2 weeks. Prior to testing, the frozen
specimen must be completely thawed, thoroughly mixed, and brought to room
temperature.
Assay Procedure
1.
Remove the test strip from its foil pouch.
2.
Holding the strip vertically, carefully dip it into the specimen. Do not
immerse the strip past the maximum line (Figure 1).
3.
The strip can be removed from the specimen when red-dye begins to
migrate through the Result Window. Interpret test results at 3 to 5 minutes.
Do not interpret test results after 5 minutes.
Interpretation of Results
(1) NEGATIVE: If there is only one purple color band in the result window, this
indicates that the specimen does not contain a detectable level of hCG and should
be interpreted as a negative result (Figure 2).
Interference Data
Potentially interfering drugs, protein and glucose were supplemented to normal
urine specimens devoid of hCG. Baseline urine level, as well as 20 mIU/ml hCG
standards were then analyzed and compared with all samples containing a specific
concentration of an interfering substance.
Substances
Acetaminophen, 20 mg/dl
Acetylsalicylic acid, 20 mg/dl
Ascorbic acid, 20 mg/dl
Atropine, 20 mg/dl
Caffeine, 20 mg/dl
Gentistic acid, 20 mg/dl
Glucose, 2000 mg/dl
Hemoglobin, 500 mg/dl
Mestranol, 3 mg/dl
Penicillin, 40,000 U/dl
Tetracycline, 20 mg/dl
(2) POSITIVE: If there are two purple color bands in the result window, this
indicates that the specimen contains hCG and should be interpreted as positive
result (Figure 2).
(3) INVALID: If there is no purple color band in the result window, the test result
is invalid. The control band will not appear if an insufficient volume of specimen
is added into the test kit. Proper procedures may not have been followed in
performing the test or deterioration of the test kit may have occurred. Repeat the
test procedure using a new test kit.
Conclusion: All of the above substances have no interference with the results of
the urine test kits.
Note: The instructions provided must be strictly followed in order to achieve
optimal test reactivity with the urine specimens.
Accuracy
The hCG Urine test compared with a commercially available urine tests (Table).
Limitations of the Procedure
1.
The Urine hCG Pregnancy Test is for in vitro diagnostic use only.
2.
In addition to pregnancy, hCG has been found in patients with both
gestation and non-gestation trophoblastic diseases. These conditions should
be ruled out when interpreting hCG levels to establish a pregnancy
diagnosis.
3.
Although the test is very accurate in detecting pregnancy a low incidence
of false results can occur. Other clinically available tests are required if
questionable results are obtained. Consult with a physician if unexpected
or inconsistent results are obtained.
4.
A normal pregnancy cannot be distinguished from an ectopic pregnancy
based solely on hCG levels. Also, a spontaneous miscarriage may cause
confusion in interpreting test results.
5.
As with all diagnostic tests, a definitive clinical diagnosis should not be
based on the results of a single test, but should only be made by the
physician after all clinical and laboratory findings have been evaluated.
6.
A negative result obtained from a urine specimen collected from a mother
in very early pregnancy may be due to an extremely low concentration of
hCG. In such cases, the test should be repeated on a fresh specimen
obtained two days later.
7.
If a urine sample is too dilute (i.e. low specific gravity), it may not contain
a representative urinary hCG concentration. If a negative result is obtained
with a low specific gravity specimen and pregnancy is still suspected,
obtain a first morning urine specimen and retest.
urine
test
Negative
Positive
Total
A commercial hCG urine test
Negative
Positive
Total
50
0
50
0
50
50
50
50
100
The conclusion is the hCG Urine strip format is comparable with a commercially
available hCG urine test.
References
1. E.A. Lenton, LM. Neal, and Sulaiman. R. Fertil, Steril., Vol. 37 (1982),
p773.
2. E. F. Batzer. Fertil, Steril., Vol. 34 (1980), p1.
3. N. W. Tietz. Clinical Guide to Lab. Tests, 2nd ed., p128, 1990.
Expected Normal Values
Urine hCG levels during pregnancy are estimated to be (1,2,3):
R04-110hCG